1. Field of the Invention
The present invention relates to mines, and in particular to devices for disabling a mine.
2. Description of Related Art
Land mines are still considered a necessary part of warfare. Of course, a lingering problem is finding, and disabling or destroying the land mines after hostilities cease. While combatants may try to make maps indicating locations of land mines, these maps are often hastily made and inaccurate, or are lost in the destruction that is part of armed conflict. Oftentimes, there is simply not the resources available to devote the time needed for carefully tracking down, and extracting or detonating these mines.
In U.S. Pat. No. 5,415,103 an interrogation unit can program a land mine to set the conditions under which the land mine will detonate. The specification states that xe2x80x9cremote communication may be performed with certain lines for activation and deactivation.xe2x80x9d Column 1, lines 16-17. The electrical firing circuit of U.S. Pat. No. 5,218,574 provides several operating modes for a land mine. In one mode, an electrolytic timing device can detonate the land mine after a predetermined delay.
These references do not disclose any mechanisms for disabling a land mine. While electronics can be fabricated to perform a variety of sophisticated functions, the mechanical process of disabling the mine is extremely important. This mechanism must be highly reliable so that it does not run the risk of detonating the mine before it is placed. On the other hand, a mechanism must also be designed to (a) avoid premature disabling, and (b) reliably disable a mine when appropriate. Because of the dangerous nature of a mine, the mechanism must be made relatively simple and must have mechanisms that are unlikely to bind, jam, or otherwise fail.
In U.S. Pat. No. 4,856, 431 a directional mine is armed by inserting firing unit 6, which is locked into place by pin 15. The mine can be detonated by firing the igniter 11. After a pre-programmed amount of time, however, an electromagnet retracts pin 15 to eject unit 17, thereby disarming the mine. This reference is relatively complicated and does not show a movable element that is inserted into a blocking position to disable a land mine after it is armed.
In U.S. Pat. No. 4,712,478 slider 30 has a passage that moves into position just before detonation to create a firing path. The land mine can be neutralized by an undefined circuit that fires detonator 44 before slider 30 is in the armed position. Alternatively, the battery that operates circuit 10 can run down and disable the land mine. This reference does not disclose a blocking element that is inserted into a blocking position to disable the land mine after it is armed.
In U.S. Pat. No. 4,854,239 a munition is fired by two explosively powered pistons if they are fired in a proper sequence before a third piston is fired. Premature firing of the third piston will fracture a component, which is then elevated to indicate the munition is disabled. Again, this complicated reference does not show a blocking element for disabling a land mine after it is armed.
See also U.S. Pat. Nos. 3,667,387 and 3,994,227.
Accordingly, there is a need for a mechanism for disabling a mine in a simple and highly reliable fashion.
In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a mine having the ability to change from an armed state to a safe state without touching of the mine. The mine includes a case and an explosive charge in the case. Also included is a detonator located adjacent to the explosive charge. The firing of the detonator can set off an explosive chain for exploding the explosive charge. The mine includes a movable firing pin mounted in the case for striking and firing the detonator in response to pressure directed toward the case. The mine also includes a blocking member adapted to move from a retracted position to a blocking position between the detonator and the firing pin in order to prevent firing of the detonator by the firing pin. Also included is a driver for moving the blocking member from the retracted position to the blocking position without manual touching of the case.
By employing the foregoing principles, an improved mine is achieved. In a preferred embodiment, a blocking member is slidably mounted in a mine and can move into a position between a firing pin and detonator to disable the mine. In one embodiment an electromagnet is energized with a polarity to repel a permanently magnetized element. If the electromagnet is disabled, the permanently magnetized element is drawn to the electromagnet to pull a flexible foam member in position between the firing pin and detonator.
This electromagnet can be disabled in a variety of ways. A circuit driving the electromagnet can have a timer that interrupts current to the electromagnet after a predetermined delay interval. Alternatively, a battery powering the electromagnet can simply run down. In some embodiments a radio receiver can detect and decode an encrypted command signal and then fire a firing cap to explode the mine.
In other embodiments, a spring loaded plunger can be biased to thrust a blocking member between the firing pin and detonator. A solenoid-like electromagnet, when energized, can pull the plunger and retract the blocking member to arm the mine. Again, interruption of the drive to the electromagnet will cause the blocking member to be thrust between the firing pin and detonator. In still other embodiments, a catch can hold a spring biased plunger in place until released by a separate releasing device.